Hydroelectric power comes from the force of flowing water rotating a turbine and a generator. This force of water is typically taken from dammed water in a reservoir. This method is known as impoundment. The force of the water flow is dependent upon the volume of water and the difference in height of the water’s source and its output through a pipe which leads to the turbine. There are additional methods such as pumped storage which uses the force of water pumped between two reservoirs; run of the river or diversion which utilizes no reservoir but instead uses the force of running river water by diverting it through a canal or penstock; and tidal power which relies on the rise and fall of water levels due to tides.

Depending on the size of these sites, they may contain their own power facilities if large enough or they may be connected to a local conventional distribution network.

Larger facilities contain a powerhouse where the turbines produce ac current which is sent to a transformer which converts it to a higher voltage for transmission through power lines.

Such facilities require many forms of safety identification. Control panels will require faceplates to identify switches and controls. Electrical transformers typically display KVA voltage ratings with reflective KVA labels. Additional transformer labels warn of high voltage and proper clearance areas. Arc flash labels also warn of the dangers of extreme voltages and dangerous arc flashes of power. Lockout tags and lockout programs are vital to protect workers from unexpected re-energizing of equipment during routine maintenance or repairs.


Identification of wiring, cables and circuitry involves durable wire and cable markers, voltage markers, phase tags and terminal markers to coordinate electrical connections.

Exterior safety and warning signage is used to mark perimeter enclosures around substations and switchgear. These include substation name signs, high voltage signs and video surveillance signs.